ABSTRACT
In this paper, a comprehensive transient three-dimensional model for heat transfer performance and flow resistance is applied to investigate the characteristics of a fin-and-tube heat exchanger with an H-typed fin. The overall and local dynamic response performance of Nu number and Eu number under volatile flow conditions are analyzed in detail. The results indicate that for the H-typed fin-and-tube heat exchanger, both the heat transfer and the fluid flow are influenced by volatile flow, which consists of three key parameters, time-averaged velocity, volatile amplitude, and the cycle time. Correlations of Nu number and Eu number for each case of volatile flow conditions are presented.
Nomenclature
a | = | thermal diffusivity, m2 s−1 |
A | = | heat transfer area, m2 |
Ac | = | cross-sectional area, m2 |
Au | = | oscillation amplitude |
cp | = | fluid specific heat, J kg−1 K−1 |
D | = | tube outside diameter, m |
De | = | equivalent diameter, m |
Fp | = | fin pitch, m |
Ft | = | fin thickness, m |
h | = | heat transfer coefficient, W m−2 K−1 |
H | = | fin height, m |
N | = | tube row number |
p | = | pressure, Pa |
P | = | wetting perimeter, m |
qm | = | mass flow rate, kg s−1 |
Q | = | heat transfer rate, W |
S1 | = | spanwise tube pitch, m |
S2 | = | longitudinal tube pitch, m |
t | = | time, s |
T | = | temperature, K |
ΔTm | = | logarithmic-mean T difference, K |
Tu | = | oscillation period, s |
u, v, w | = | x, y, z velocity components, m s−1 |
U | = | velocity magnitude, m s−1 |
W | = | slit width, m |
x, y, z | = | Cartesian coordinates |
Greek symbols | = | |
λ | = | thermal conductivity, W m−1 K−1 |
ν | = | kinematic viscosity, m2 s−1 |
ρ | = | fluid density, kg m−3 |
Dimensionless numbers | = | |
Re | = | Reynolds number |
Nu | = | Nusselt number |
Eu | = | Euler number |
Subscripts | = | |
in, out | = | channel inlet and outlet |
w | = | fin surface |
max | = | maximum value |
min | = | minimum value |
Nomenclature
a | = | thermal diffusivity, m2 s−1 |
A | = | heat transfer area, m2 |
Ac | = | cross-sectional area, m2 |
Au | = | oscillation amplitude |
cp | = | fluid specific heat, J kg−1 K−1 |
D | = | tube outside diameter, m |
De | = | equivalent diameter, m |
Fp | = | fin pitch, m |
Ft | = | fin thickness, m |
h | = | heat transfer coefficient, W m−2 K−1 |
H | = | fin height, m |
N | = | tube row number |
p | = | pressure, Pa |
P | = | wetting perimeter, m |
qm | = | mass flow rate, kg s−1 |
Q | = | heat transfer rate, W |
S1 | = | spanwise tube pitch, m |
S2 | = | longitudinal tube pitch, m |
t | = | time, s |
T | = | temperature, K |
ΔTm | = | logarithmic-mean T difference, K |
Tu | = | oscillation period, s |
u, v, w | = | x, y, z velocity components, m s−1 |
U | = | velocity magnitude, m s−1 |
W | = | slit width, m |
x, y, z | = | Cartesian coordinates |
Greek symbols | = | |
λ | = | thermal conductivity, W m−1 K−1 |
ν | = | kinematic viscosity, m2 s−1 |
ρ | = | fluid density, kg m−3 |
Dimensionless numbers | = | |
Re | = | Reynolds number |
Nu | = | Nusselt number |
Eu | = | Euler number |
Subscripts | = | |
in, out | = | channel inlet and outlet |
w | = | fin surface |
max | = | maximum value |
min | = | minimum value |